1. Field of the Invention
The present invention relates to imaging lenses and imaging apparatuses. More specifically, the invention relates to an imaging lens suited for use in compact imaging apparatuses using a solid state imaging device, such as a charge coupled device (CCD) or complementary metal-oxide semiconductor (CMOS) and to an imaging apparatus using the lens.
2. Description of the Related Art
As apparatuses using a solid state imaging device, such as a CCD or CMOS, camera-enabled mobile phones, digital still cameras, and such other apparatuses are known. In the field of such imaging apparatuses, further size reduction or compactness is demanded, so that an imaging lens being mounted therein is required to have a reduced total length (total lens length).
Generally known imaging lenses being used for the above purposes include types of, for example, a doublet configuration and triplet configuration. For example, types as disclosed in Japanese Unexamined Patent Application Publication No. 2003-215446 and No. 2004-4566 are known.
In recent years, in the field of compact imaging apparatuses, such as camera-enabled mobile phones, technology is advanced for enhancement in compactness and high pixel density of imaging devices, and models with high pixel density imaging devices on mega-pixel or higher orders are marketed as popular apparatuses. Under these circumstances, a requirement for high lens performance corresponding to such high-pixel density solid state imaging devices is placed on an imaging lens being mounted.
In the case of the imaging lens disclosed in Japanese Unexamined Patent Application Publication No. 2003-215446, however, while doublet configuration and compactness are implemented, various types of substantial aberrations take place. In this case, the requirement for lens performance suitable to the high-pixel density imaging device cannot be satisfied. In the case of the imaging lens disclosed in Japanese Unexamined Patent Application Publication No. 2004-4566, although the lens has lens performance corresponding to a today's high-pixel density imaging device, the number of lenses is as large as three. In this case, physical constraints take place, thereby making it difficult to implement further compactness.